End-of-life pathways for photovoltaic backsheets

Using life cycle assessment, scientists at UMSICHT have compared the environmental impacts stemming from the End-of-life (EOL) treatment of fluorine-free and fluorinated backsheet material used in photovoltaic modules. They focused on three potential EOL scenarios – incineration, pyrolysis and landfilling – as well as two commonly used backsheet materials: fluorine-free backsheets based on polyethylene terephthalate (PET) and fluorinated backsheets based on polyvinylidene fluoride (PVDF).

Investments in the photovoltaic sector have been soaring globally since early 2000s. Consequently, the amount of photovoltaic waste is increasing, too. The total amount of photovoltaic waste generated globally reached 45 thousand tonnes in 2016, and is projected to increase to 60 million tonnes by 2050.

This waste contains both valuable resources and hazardous substances. The recoverable valuables include aluminum, copper, and glass, which are already being recycled today. The hazardous substances are cadmium, arsenic, lead, antimony, and fluoropolymers. Hence, proper handling of these substances at their EOL must be considered, not only to prevent environmental damage but also to prevent the loss of resources.

The life cycle assessment for the fluorine-free backsheets show better environmental performance compared to the fluorinated backsheets in both incineration as well as the pyrolysis EOL scenarios.

In the incineration scenario, the environmental impact of fluorine‐free backsheets is clearly better than fluorinated backsheets in 11 out of 12 investigated impact categories. Likewise, in the pyrolysis scenario, fluorine‐free backsheets show better environmental performance than fluorinated backsheets in 8 out of 12 impact categories.

Pyrolysis could be a potential end-of-life treatment option for fluorine-free backsheets. It is however not a viable option for fluorinated backsheets due to high amounts of hydrogen fluoride produced in addition to the halogenated hydrocarbons in the pyrolysis oils which pose a potential environmental hazard.

• COVEME S.p.A., Italien